The pour point of paraffin-containing liquids is reduced by adding to the liquid an effective amount of a pour point depressant which is the reaction product of a hydrocarbyl-substituted phenol having a number average of greater than 30 carbon atoms in the hydrocarbyl-substituent, and an aldehyde of 1 to about 12 carbon atoms, or a source therefor. The pour point depressant is particularly useful for treating crude oils which have an initial pour point of 4.degree. C. or higher.